Full list of all 78 For The King achievements. It takes around 80-100 hours to unlock all of the achievements in the base game on Windows.
The base game contains 72 achievements, and there is 1 DLC pack containing 6 achievements.
Defeat the Cultist Camp
Purge the Glittering Mines
Have 300 Gold
Clear 5 Sea Caves in 1 game
Complete 1 Side Quest
Defeat the Foul Priestess
Clear the Forgotten Cellar
Defeat the Lich's Crypt
Defeat the Mind Bender
Fly in the Air Balloon
Defeat Vexor on Apprentice
Defeat Vexor on Journeyman
Defeat Vexor on Master
Solve the King's Maze
Purge the Buried Temple
Clear a Cave
Clear the Flooded Crypt
Escape the Mage Dungeon
Reach the top of Harazuel
Survive the Lava Dungeon
Defeat the Chaos Beast
First party wipe
Revive a party member
Break a weapon
Complete 50 Side Quests
Have 1500 Gold
Have 5000 Gold
Clear both Demon Caves
Defeat Lucky
Defeat the Bandit King
Defeat the Royal Droll
Defeat the Hangman
Defeat Coal Heart
Defeat the Old One
Honor 3 Stone Heros
Honor 15 Stone Heros
Honor 50 Stone Heros
Kill the Kraken
Kill a thief attempting to flee
Kill 1000 Enemies
Defeat 100 Beastmen
Smash 150 Skellys
Murder 30 Hags
Defeat 3 Triclops
Defeat 10 Mimics
Topple 15 Crag Monsters
Crush 25 Imps
Unlock 1 item from the Lore Store
Unlock 20 items from the Lore Store
Unlock 40 items from the Lore Store
Slay the dragon at the top of Frostbite Peak
Defeat the Yeti, free her "prisoner"
Unlock the armory
Break a sieged town
Kill 5 Snowmen
Help Hildebrant retrace his steps
Defeat Deimos
Defeat Disciple
Use 100 herbs
Use 10 candies
Enter Hildebrant's Cellar
Reach the bottom of Hildebrant's Cellar
Reach the Inferno
Win a game of Gold Rush
Find Bradach's Cabin
Purge all 4 Water Temples
Find Captain Greenbeard's Ship
Defeat the Sea King
Defeat the Songstress
Kill 30 Fishfolk
Kill 10 enemies with Firearms
Get killed by a suicidal enemy